include/linux/iocontext.h

   1 #ifndef IOCONTEXT_H
   2 #define IOCONTEXT_H
   3
   4 #include <linux/radix-tree.h>
   5 #include <linux/rcupdate.h>
   6
   7 /*
   8  * This is the per-process anticipatory I/O scheduler state.
   9  */
  10 struct as_io_context {
  11         spinlock_t lock;
  12
  13         void (*dtor)(struct as_io_context *aic); /* destructor */
  14         void (*exit)(struct as_io_context *aic); /* called on task exit */
  15
  16         unsigned long state;
  17         atomic_t nr_queued; /* queued reads & sync writes */
  18         atomic_t nr_dispatched; /* number of requests gone to the drivers */
  19
  20         /* IO History tracking */
  21         /* Thinktime */
  22         unsigned long last_end_request;
  23         unsigned long ttime_total;
  24         unsigned long ttime_samples;
  25         unsigned long ttime_mean;
  26         /* Layout pattern */
  27         unsigned int seek_samples;
  28         sector_t last_request_pos;
  29         u64 seek_total;
  30         sector_t seek_mean;
  31 };
  32
  33 struct cfq_queue;
  34 struct cfq_io_context {
  35         void *key;
  36         unsigned long dead_key;
  37
  38         struct cfq_queue *cfqq[2];
  39
  40         struct io_context *ioc;
  41
  42         unsigned long last_end_request;
  43         sector_t last_request_pos;
  44
  45         unsigned long ttime_total;
  46         unsigned long ttime_samples;
  47         unsigned long ttime_mean;
  48
  49         unsigned int seek_samples;
  50         u64 seek_total;
  51         sector_t seek_mean;
  52
  53         struct list_head queue_list;
  54         struct hlist_node cic_list;
  55
  56         void (*dtor)(struct io_context *); /* destructor */
  57         void (*exit)(struct io_context *); /* called on task exit */
  58
  59         struct rcu_head rcu_head;
  60 };
  61
  62 /*
  63  * I/O subsystem state of the associated processes.  It is refcounted
  64  * and kmalloc'ed. These could be shared between processes.
  65  */
  66 struct io_context {
  67         atomic_t refcount;
  68         atomic_t nr_tasks;
  69
  70         /* all the fields below are protected by this lock */
  71         spinlock_t lock;
  72
  73         unsigned short ioprio;
  74         unsigned short ioprio_changed;
  75
  76         /*
  77          * For request batching
  78          */
  79         unsigned long last_waited; /* Time last woken after wait for request */
  80         int nr_batch_requests;     /* Number of requests left in the batch */
  81
  82         struct as_io_context *aic;
  83         struct radix_tree_root radix_root;
  84         struct hlist_head cic_list;
  85         void *ioc_data;
  86 };
  87
  88 static inline struct io_context *ioc_task_link(struct io_context *ioc)
  89 {
  90         /*
  91          * if ref count is zero, don't allow sharing (ioc is going away, it's
  92          * a race).
  93          */
  94         if (ioc && atomic_inc_not_zero(&ioc->refcount)) {
  95                 atomic_inc(&ioc->nr_tasks);
  96                 return ioc;
  97         }
  98
  99         return NULL;
 100 }
 101
 102 #endif